A severe service disruption on Thursday along Hong Kong’s key commuter railway line to the Shenzhen border left thousands of passengers stranded and scrambling for alternative transport during the evening rush hour.

There was chaos at East Rail line stations after an overhead cable near Hung Hom suddenly snapped – a rare occurrence – at around 3pm, knocking out power and disrupting train services for 41/2 hours.

Critics urged the MTR Corporation to review its inspection procedures, suggesting that it was outdated and technical staff might have overlooked the wear and tear of overhead cables by simply relying on naked-eye monitoring.

“It’s very rare that an overhead cable suddenly snapped. It showed that there is something wrong with the MTR’s inspection mechanism. It needs to review the system or consider using rigid overhead conductors to replace cables,” pro-establishment lawmaker and rail expert Michael Tien Puk-sun said.

The breakdown first brought a train to a sudden halt 400 metres from Mong Kok East station, forcing some 110 passengers to get off and walk along the tracks to the nearest platform.

The MTR said it immediately mobilised staff to help, but many commuters complained about having to walk on the tracks. An elderly man holding his grandson by the hand had to be carted off in a wheelchair.

From 3pm to 5.30pm, services between Kowloon Tong and Hung Hom were completely suspended, while trains between Kowloon Tong and Lok Ma Chau stations ran at 20-minute intervals, and every 10 minutes between Kowloon Tong and Lo Wu stations.

The intercity service between Guangzhou and Hong Kong, which uses the same track, was also suspended.

At 5.30pm, as repairs progressed, the suspension was confined to services between Hung Hom and Mong Kok East stations. Trains between Mong Kok East and Lok Ma Chau ran at 12-minute intervals, and the frequency reduced to four minutes between Mong Kok East and Lo Wu .

Normal services along the whole line resumed at 7.30pm. Commuters at the tail end of the evening rush hour scrambled back to station platforms as the announcement was made.

The MTR’s head of infrastructure works, Lu Wong Ho-leung, explained later that a section of the overhead cable between Hung Hom and Mong Kok East had snapped, causing the power failure. The roof of the train that stopped on the tracks was also damaged.

“After receiving the report, our engineering teams have been working hard to repair the damage and ensure other components are safe in the hope of resuming normal service as soon as possible,” he said.

Kowloon Tong station, where passengers interchange between the East Rail and Kwun Tong lines, was uncharacteristically empty from 6 to 6.30pm. At the same time, at Hung Hom, lines formed for free shuttle buses to Kowloon Tong arranged by the MTR.

I don’t think the MTR should have so many delays while making so much profit

Stanley Wong, passenger

Stanley Wong, who works in Wan Chai, said he expected to arrive home in Sheung Shui 30 minutes later than usual.

“I don’t think the MTR should have so many delays while making so much profit,” Wong said as he waited to board a bus.

Cindy Ng, a security guard in the queue, said it was the second time she had encountered an MTR service delay this year.

“I don’t have other options to go back to Tai Wo,” she said. “It’s okay as long as they provide free buses.”

The rail operator came under fire just last month for causing transport chaos with another service disruption in east Kowloon on the night of April 10. A power fault halted MTR trains between Kwun Tong and Kowloon Tong for more than two hours, forcing thousands of stranded passengers to join long queues for shuttle buses or other public transport.

At Choi Hung station, passengers were forced to leave a stranded train in a tunnel and walk along the tracks after the electricity supply was cut.